Seventh seeds Paes and Stepanek caused a major upset beating formidable top seeds Mike and Bob Bryan 6-4 6-4, but the pair of Mahesh Bhupathi and Rohan Bopanna went down 2-6 4-6 against second seeded Max Mirnyi of Belarus and Canada's Daniel Nestor.
The possibility of an almost Indian showdown in the ATP Miami Masters final was wiped out in the semifinals after the results.
Paes and Stepanek, who had defeated the Bryan brothers in the Australian Open title clash earlier this year, took an hour and 11 minutes to topple their opponents.
The Indo-Czech combo go into the final without having dropped a set in the tournament so far.
They won a total of 66 points as compared to 43 by the Americans during their semifinal encounter.
However, Paes and Stepanek could convert only three out of as many as 11 breakpoints they got.
Meanwhile, the sixth seeded Bhupathi and Bopanna lost in less than an hour to the Belarus-Canadian pair.
The Indians, who had recently won the Dubai Duty Free Tennis Championship, failed to convert any of the six breakpoints that they got.
Though they managed to save three of the six breakpoints received by Mirnyi and Nestor.